US4258335A - Gas laser - Google Patents

Gas laser Download PDF

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Publication number
US4258335A
US4258335A US05/955,746 US95574678A US4258335A US 4258335 A US4258335 A US 4258335A US 95574678 A US95574678 A US 95574678A US 4258335 A US4258335 A US 4258335A
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United States
Prior art keywords
plate
metal
edge
metal plate
insulating plate
Prior art date
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Expired - Lifetime
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US05/955,746
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English (en)
Inventor
Jerome Donon
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Alcatel Lucent SAS
Original Assignee
Compagnie Generale dElectricite SA
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Publication date
Application filed by Compagnie Generale dElectricite SA filed Critical Compagnie Generale dElectricite SA
Assigned to SOCIETE ANONYME DITE: COMPAGNIE GENERALE D'ELECTRICITE reassignment SOCIETE ANONYME DITE: COMPAGNIE GENERALE D'ELECTRICITE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: DONON JEROME
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/097—Processes or apparatus for excitation, e.g. pumping by gas discharge of a gas laser
    • H01S3/0971—Processes or apparatus for excitation, e.g. pumping by gas discharge of a gas laser transversely excited
    • H01S3/0973—Processes or apparatus for excitation, e.g. pumping by gas discharge of a gas laser transversely excited having a travelling wave passing through the active medium

Definitions

  • the present invention relates to a gas laser and in particular to a laser in which an active gaseous medium is excited by a wave of electric current propagating along a flat plate transmission line.
  • a flat plate transmission line is made of an insulating plate placed between two metal plates.
  • a current wave can be caused to propagate along the line by bringing the plates to different potentials and then generating an electric discharge between them.
  • gas lasers of this type cease to function after a relatively short period of operation. Initially, erosion of the insulating material is observed on the edge of the transmission line, followed by peripheral breakdown between the metal plates.
  • Breakdown occurs even if care is taken to let the insulating plate extend beyond the metal plates.
  • the present invention aims to mitigate this disadvantage and to increase the reliability of gas lasers excited by means of a flat plate transmission line.
  • the present invention provides a gas laser which comprises:
  • a first metal plate which partially covers a first surface of the insulating plate, the uncovered part of the first surface forming a first peripheral strip which surrounds the edges of the first metal plate, the metal plate being divided into two distinct portions by a rectilinear slot;
  • a second metal plate which partially covers the second surface of the insulating plate, the uncovered part of the second surface forming a second peripheral strip which surrounds the edges of the second metal plate;
  • FIG. 1 is a cross-sectional view of a first embodiment of a gas laser in accordance with the invention
  • FIG. 2 is a partial cross-sectional view of a second embodiment of a gas laser in accordance with the invention.
  • FIG. 3 is a partial cross-sectional view of a third embodiment of a gas laser in accordance with the invention.
  • a horizontal insulating plate 1 is placed between two metal plates.
  • One of the metal plates covers the upper surface of the insulating plate 1; it is divided into two distinct portions 2 and 3 by a rectilinear slot 4.
  • the metal plate only partially covers the upper surface of the insulating plate 1.
  • the uncovered part of the upper surface forms a peripheral strip 5 which extends from the edge 14 of the metal plate 2-3 to the edge 16 of the insulating plate 1; the strip therefore surrounds the metal plate 2-3.
  • the ends of an induction coil 6 are connected to respective ones of the portions 2 and 3 of the metal plate.
  • Another metal plate 7 is disposed on the lower surface of the plate 1 and partially covers said surface, also leaving a peripheral strip 8 of the surface uncovered.
  • the two terminals of a high-voltage electric generator 9 are connected respectively to the portion 2 of the upper metal plate and to the lower metal plate 7.
  • An auxiliary laser generator 10 supplied by a circuit 11 effects a laser radiation pulse 18 which is directed towards the portion 2 of the plate 2-3.
  • An insulating plate 12 presses against the upper surface of the plate 2-3 on both sides of the slot 4.
  • a semi-conductor layer 13 is disposed on the peripheral strip 5, in contact with the edge 14 of the plate 2-3.
  • the layer covers the whole surface of the peripheral strip 5 except for a marginal zone 15 delimited on the outside by the edge 16 of the insulating plate 1.
  • the layer 13 also partially covers the upper surface of the metal plate 2-3 in the proximity of its edge 14.
  • the layer 13 is preferably formed by graphite-impregnated epoxy paint; the paint is applied with a brush, for example.
  • the gas laser illustrated in FIG. 1 operates as follows.
  • An active gas such as air or nitrogen at normal pressure is contained in the slot 4.
  • the active gas is air at normal atmospheric pressure, it is not necessary to dispose the plate 12 on the slot or to close off the ends of the slot. In the contrary case, the gas is enclosed in the slot by means of the plate 12 and of two windows placed at the ends of the slot.
  • the flat plate transmission line constituted by the metal plates 2-3 and 7 placed on either side of the insulating plate 1 is charged by the generator 9, the portion 3 of the upper metal plate being charged via the induction coil 6.
  • a pulse 18 of the auxiliary laser 10 is triggered, said pulse being concentrated at a point of the portion 2 of the upper metal plate.
  • the discharge generates a circular current wave which propagates in the flat plate transmission line.
  • the edges 14 of the plate 2-3 are parabolic with the pulse 18 being concentrated on the focus of the parabola.
  • the circular current wave is therefore transformed into a rectilinear wave by reflection on the edges of the parabola.
  • the wave successively reaches the active molecules of gas situated along the slot 4, forming a laser beam which propagates along the rectilinear slot 4.
  • the surface electric field set up by the live metal plates on the surface of the insulating plate 1, for example, at 19 is reduced progressively from the edge 14 of the metal plate 2-3 towards the edge 16 of the insulating plate 1. This reduction is explained by the fact that the resistivity of the layer 13 is very much greater than that of the metal which constitutes the metal plates, which are usually copper plates.
  • the metal plate 7 For the reduction of the electric field to be effective, it is necessary for the metal plate 7 to cover the lower surface of the plate 1 at least up to the edge of the layer 13, as shown in the figure.
  • the edge 20 of the metal plate 7 is substantially opposite to the edge 21 of the layer 13, on respective sides of the insulating plate.
  • the width of the peripheral strip 8 is then substantially equal to that of the marginal zone 15.
  • the marginal zone 15 makes it possible to avoid direct breakdown between the layer 13 and the plate 7 at the edge of the electric line, in the case where there remains an appreciable electric tension at that point.
  • the partial covering 17 of the plate 2-3 by the layer 13 is intended to provide excellent electric contact between the layer 13 and the plate 2-3.
  • the thickness of the layer 13 can lie between 0.1 mm and 2 mm, while its width can be about 4 to 5 cm and the width of the marginal zone can be about one centimeter.
  • a semiconductor layer analogous to the layer 13 can also be disposed on the other surface of the plate 1.
  • the marginal zones which are not covered by these layers will preferably have substantially equal widths.
  • the period of operation without breakdown of gas lasers provided with such semiconductor layers is greatly lengthened, e.g. doubled or trebled, in relation to that of gas lasers in accordance with prior art.
  • FIG. 2 illustrates another embodiment of the invention in which annular metal rings 22, 23, 24 and 25 are spaced apart from one another round the metal plate 2-3 and are applied against the upper surface of the plate 1 in the peripheral strip.
  • These metal plates are preferably made of the same material as the metal plates 2-3 and 7.
  • the surface electric field is progressively reduced by depositing, in the interstices, semiconductor layers made of the same material as the layer 13 (FIG. 1).
  • peripheral metal rings 22 to 25 are disposed in an exactly analogous way to that illustrated in FIG. 2, but here, the semiconductor layers are replaced by capacitors such as 29,30,31,32.
  • the plates of the capacitor 29 are connected respectively to the plate 2-3 and to the plate 22, while the plates of each of the other capacitors are connected respectively to two consecutive rings. These connections can be made with a conductive adhesive.
  • the surface electric field is reduced in steps, from one metal ring to the next by capacitors.
  • Gas lasers in accordance with the invention can be applied to the remote detection of polluting gases in the atmosphere.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Lasers (AREA)
  • Semiconductor Lasers (AREA)
US05/955,746 1977-11-24 1978-10-30 Gas laser Expired - Lifetime US4258335A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7735376A FR2410382A1 (fr) 1977-11-24 1977-11-24 Laser a gaz
FR7735376 1977-11-24

Publications (1)

Publication Number Publication Date
US4258335A true US4258335A (en) 1981-03-24

Family

ID=9198009

Family Applications (1)

Application Number Title Priority Date Filing Date
US05/955,746 Expired - Lifetime US4258335A (en) 1977-11-24 1978-10-30 Gas laser

Country Status (10)

Country Link
US (1) US4258335A (xx)
JP (1) JPS5479586A (xx)
BE (1) BE871784A (xx)
CH (1) CH627306A5 (xx)
DE (1) DE2849999A1 (xx)
FR (1) FR2410382A1 (xx)
GB (1) GB2008845B (xx)
IT (1) IT1108450B (xx)
NL (1) NL7811422A (xx)
SE (1) SE7811279L (xx)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4363126A (en) * 1980-12-10 1982-12-07 United Technologies Corporation Tuned-circuit RF-excited laser
WO1986003212A1 (en) * 1984-11-21 1986-06-05 Stamicarbon B.V. Polyamide resin compositions
US4596018A (en) * 1983-10-07 1986-06-17 Minnesota Laser Corp. External electrode transverse high frequency gas discharge laser
US4622582A (en) * 1984-01-09 1986-11-11 Dainippon Screen Seizo Kabushiki Kaisha Asynchronous color image processing system with a plurality of picture input units and a plurality of picture reproducing units selected in accordance with a predetermined order of preference
US4788691A (en) * 1984-06-26 1988-11-29 Gerd Herziger Method for the operation of a gas laser and a gas laser operated in accord therewith
EP0361636A2 (en) 1988-09-30 1990-04-04 Amoco Corporation Polyamide-polyarylene sulfide blends
US6792011B2 (en) * 2001-04-19 2004-09-14 Hrl Laboratories, Llc Frequency modulated laser with high modulation bandwidth

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3936946C2 (de) * 1989-11-06 1995-02-16 Stefan Zoepfel Kontinuierlicher Edelgas - Halogenid- bzw. Edelgas - Halogen Excimerlaser

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3882418A (en) * 1973-06-22 1975-05-06 Comp Generale Electricite Parallel plate transmission line laser excitation system
US3935544A (en) * 1973-12-27 1976-01-27 Compagnie Generale D'electricite Gas laser structure for eliminating parasitic arcing

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3882418A (en) * 1973-06-22 1975-05-06 Comp Generale Electricite Parallel plate transmission line laser excitation system
US3935544A (en) * 1973-12-27 1976-01-27 Compagnie Generale D'electricite Gas laser structure for eliminating parasitic arcing

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
James G. Small's; "An unusual kind of gas laser that puts out pulses in the ultraviolet", Scientific American, (Jun. 1974), pp. 122-126; conducted by C. L. Stong. *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4363126A (en) * 1980-12-10 1982-12-07 United Technologies Corporation Tuned-circuit RF-excited laser
US4596018A (en) * 1983-10-07 1986-06-17 Minnesota Laser Corp. External electrode transverse high frequency gas discharge laser
US4622582A (en) * 1984-01-09 1986-11-11 Dainippon Screen Seizo Kabushiki Kaisha Asynchronous color image processing system with a plurality of picture input units and a plurality of picture reproducing units selected in accordance with a predetermined order of preference
US4788691A (en) * 1984-06-26 1988-11-29 Gerd Herziger Method for the operation of a gas laser and a gas laser operated in accord therewith
WO1986003212A1 (en) * 1984-11-21 1986-06-05 Stamicarbon B.V. Polyamide resin compositions
EP0361636A2 (en) 1988-09-30 1990-04-04 Amoco Corporation Polyamide-polyarylene sulfide blends
US6792011B2 (en) * 2001-04-19 2004-09-14 Hrl Laboratories, Llc Frequency modulated laser with high modulation bandwidth

Also Published As

Publication number Publication date
NL7811422A (nl) 1979-05-28
FR2410382B1 (xx) 1980-10-31
IT7869561A0 (it) 1978-11-08
BE871784A (fr) 1979-05-07
GB2008845A (en) 1979-06-06
SE7811279L (sv) 1979-05-25
CH627306A5 (xx) 1981-12-31
GB2008845B (en) 1982-02-03
DE2849999A1 (de) 1979-05-31
IT1108450B (it) 1985-12-09
FR2410382A1 (fr) 1979-06-22
JPS5479586A (en) 1979-06-25

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